981 with PDK still need DMFW

[sb01box]

Curious;
987 & 981 with PDK still require dual mass flywheel to decouple the engine and the transmission?
Or do the new design have forged crank and or beefed up engine main so DMFW is no longer needed?

[thstone]

The 981 uses a dual mass flywheel for the manual transmission, not for PDK.

[sb01box]

Originally Posted by thstone

The 981 uses a dual mass flywheel for the manual transmission, not for PDK.

my understanding is that PDK is computerized manual transmission. so it should have similar engine/transmission coupling. If PDK system does not need DMFW, and the crank is not forged, but built with the same technology as 986 or 987 (pre PDK), then what's the rationale for not needing DMFW

[stephen wilson]

The clutch is completely different on the PDK, and there's 2 of them , so they would have to find a different solution than the DMF.
2009 Porsche Panamera Gets Techy With Dual-Clutch Gearbox, Active Aerodynamics - Motor Trend WOT
( the Panamera is the first pic. I found )

[sb01box]

where I'm going with this is to link PDK mechanical design to DMFW - LWFW discussion where using LWFW will disrupt (alter) the harmonics of the crank and result in breakage.

[stephen wilson]

You're trying to make a connection where there is none.

[sb01box]

Originally Posted by stephen wilson

You're trying to make a connection where there is none.

I thought there's two features to DMFW.
1) decouples the trans from the engine when the clutch is fully engaged so as not to have two resonance beat on each other. didn't think that the difference in the clutch (wet or dry or "other") had any impact.
2) easier clutch engagement by not transferring the engine power pulse directly to the wheel.

my car has 137K miles, clutch is still good but it's getting there. so I am thinking about the LWFW path as an alternative to DMFW

[stephen wilson]

LWFW's have been discussed a ton here, some experts like JFP says it's a very bad idea, but others have run them for years with no issues. Do a search, read up, and make your decision. The PDK solution does not apply.

[sb01box]

Originally Posted by stephen wilson

LWFW's have been discussed a ton here, some experts like JFP says it's a very bad idea, but others have run them for years with no issues. Do a search, read up, and make your decision. The PDK solution does not apply.

I am not trying to be argumentative. I have looked up DMFW and in Luk's web site, there is fair amount of engineering articles on DMFW.
my question is this. two different, but basically manual transmission. one, the clutch is controlled by the driver uses DMFW, the other is computer controlled.does not appear to have such resonance isolator.
the same fundamental engine and transmission resonances exists.
so WHY "the PDK solution does not apply"? just asking a technical question.

[stephen wilson]

The PDK does not have a traditional flywheel like the 986. From what I've read, the DMFW dampens crankshaft harmonics, like old V8's have a harmonic balancer on the front. I honestly don't know what they use to counter harmonics on the PDK, or the Tiptronic for that matter. You may want to add a dampened underdrive pulley in addition to the LWFW. I'll be the first to admit I don't have all the answers.

[Cloudsurfer]

Originally Posted by sb01box

I am not trying to be argumentative. I have looked up DMFW and in Luk's web site, there is fair amount of engineering articles on DMFW.
my question is this. two different, but basically manual transmission. one, the clutch is controlled by the driver uses DMFW, the other is computer controlled.does not appear to have such resonance isolator.
the same fundamental engine and transmission resonances exists.
so WHY "the PDK solution does not apply"? just asking a technical question.

The DMFW is there to both dampen harmonics of the crank (the same way that many engines use a harmonic damper on the front crank pulley, while all but the M97 do not) AND to provide some "squish" from driveline shock getting transmitted to the crank (the alternative here being a sprung clutch friction disk).

The latter part of this is why the PDK cars do not need a DMFW. Due to the nature of being computer controlled (i.e. smooth, perfectly rev matched shifts EVERY time) and the fact that there are two clutches, one between the engine and gearbox/ one between the gearbox to the halfshafts, the "squish" factor is not needed.

Now, I'm not sure if the DFI motors are running a harmonic damper on the front crank pulley or not (haven't gotten to play with one of these yet), but I imagine they have to be damping harmonics somewhere.

[sb01box]

Originally Posted by Cloudsurfer

The DMFW is there to both dampen harmonics of the crank (the same way that many engines use a harmonic damper on the front crank pulley, while all but the M97 do not) AND to provide some "squish" from driveline shock getting transmitted to the crank (the alternative here being a sprung clutch friction disk).

The latter part of this is why the PDK cars do not need a DMFW. Due to the nature of being computer controlled (i.e. smooth, perfectly rev matched shifts EVERY time) and the fact that there are two clutches, one between the engine and gearbox/ one between the gearbox to the halfshafts, the "squish" factor is not needed.

Now, I'm not sure if the DFI motors are running a harmonic damper on the front crank pulley or not (haven't gotten to play with one of these yet), but I imagine they have to be damping harmonics somewhere.

thanks - yes, my question is the same as your last sentence. "what mechanism, if any does the pdk equipped cars have for engine/trans harmonic dampening; aka DMFW?

[Cloudsurfer]

Originally Posted by sb01box

thanks - yes, my question is the same as your last sentence. "what mechanism, if any does the pdk equipped cars have for engine/trans harmonic dampening; aka DMFW?

My guess is a harmonic damper on the front crank pulley.

[Jake Raby]

I'll post some pics from 4.2L "Cayman X" tomorrow. These will show you guys what the factory equipment looks like on the DFI engines.

I have a 2012 Cayman R apart now and can post some of those pics as well, then we have a 2014 GT3 inbound to take apart in November, too.

[sb01box]

Originally Posted by Jake Raby

I'll post some pics from 4.2L "Cayman X" tomorrow. These will show you guys what the factory equipment looks like on the DFI engines.

I have a 2012 Cayman R apart now and can post some of those pics as well, then we have a 2014 GT3 inbound to take apart in November, too.

thanks. that would be great. looking forward to tomorrow.